Three-dimensional fabric covers for seats have in the past been produced from woven or knitted fabric which has been cut into shaped panels which are then sewn together.
More recently it has been found possible to continuously knit one-piece piece upholstery fabric, which removes the need for cutting and sewing, and has the desired shape to serve as covers for the back and base cushions of motor vehicle seats; see, for example, U.S. Pat. Nos. 5,308,141 and 5,326,150.
It is necessary to provide anchorage devices at the edges of the covers to enable the covers to be secured to a support and held tautly over their respective cushions. The anchorage devices typically take the form of tubular portions which may be formed by sewing or by integrally knitting said portions. The tubular portions accommodate rods which are recessed into the cushions and secured under the support. If the base and back cushions comprise bolsters, it may also be necessary to provide anchorage devices on the undersurface of the cover in order to conform the cover to the shape of the upper surface of the cushion. The anchorage devices are typically open ended tubular flaps which are formed by sewing or integral knitting as shown in U.S. Pat. No. 5,326,150. It is difficult to hold the central panel of a seat back cover down against the foam cushion. It is not usually possible to utilize metal rods and hog rings in this region. Typically the cover is held in place by adhesives, Velcro.TM., or more usually by passing elastomeric cord through the flaps and anchoring each end of the tensioned cord to a suitable point on the seat support. These anchorage points have to be hidden from sight.
The elastomeric cord, tubular flap formation, threading of the cord and location of the anchorage means are costly.